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Abstract: An apparatus for extraction of flavonoids from Herba Epimedii has been constructed which utilizes a microwave technique for heating in a dynamic mode. A TM010 microwave resonance cavity was applied to concentrate the microwave energy; the power needed to achieve efficient extraction was significantly reduced. The method has been compared with other extraction methods, such as pressurized microwave-assisted extraction (PMAE), ultrasonic extraction (UE), heat reflux extraction (RE) and Soxhlet extraction (SOX). The four flavonoids in extract were identified by HPLC–MS. The influence of extraction parameters on the extraction yield of flavonoids has been evaluated by comparison with the peak areas of HPLC-DAD spectra in the different extraction methods. The results showed that the extraction yield of flavonoids in Herba Epimedii obtained by dynamic microwave-assisted extraction (DMAE) was higher than that obtained by UE, RE and SOX, and the extraction time is dramatically reduced. The extraction yield obtained by DMAE is similar to that obtained by PMAE. But the flavonoids in Herba Epimedii would not decompose easily when increasing the extraction time in DMAE. This is the benefit of dynamic extraction system which can transfer the analytes extracted from the sample matrix with flowed fresh solvent to the out of extraction vessel. [Copyright &y& Elsevier]

Abstract: A novel technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with high-performance liquid chromatography (HPLC) through a flow injection interface has been developed for determination of andrographolide and dehydroandrographolide in Andrographis paniculata Nees. A TM010 microwave resonance cavity built in the laboratory was applied to concentrating the microwave energy. An extraction vessel was placed in microwave irradiation zone. The extraction was performed in a recirculating system. When a number of extraction cycles were completed, the fractional extract (20μL) was driven to the analytical column by 65% aqueous methanol and was measured by diode array detector (DAD) at 225nm. The optimized extraction conditions are follows: extraction solvent 60% aqueous methanol; microwave forward power 80W; extraction time 6min; extraction solvent flow-rate 1.0mLmin−1. The detection and quantification limits obtained are 0.5 and 1.7μgmL−1 for andrographolide and 0.6 and 1.9μgmL−1 for dehydroandrographolide, respectively. The within-day and between-day precision (RSD) are 2.1% and 3.7% for andrographolide and 1.7% and 4.1% for dehydroandrographolide, respectively. Mean recoveries for andrographolide and dehydroandrographolide are 97.7% and 98.7%, respectively. Compared with ultrasonic extraction used in the Chinese pharmacopoeia, the proposed method was demonstrated to obtain higher extraction yield in a shorter time. In addition, only small quantities of solvent (5mL) and sample (10mg) were required. [Copyright &y& Elsevier]

Abstract: A rapid dynamic microwave-assisted extraction and on-line detection by spectrophotometry is proposed for the determination of safflower yellow in Flos Carthami. A high pressure and a peristaltic pump were used to deliver the solvent. A TM010 microwave resonance cavity was applied to concentrate the microwave energy and the forward power about 60W was enough for the extraction. Other extraction conditions also were examined and optimized. In this work, the extraction process can be monitored by measuring the absorption of safflower yellow in the extract, which would be convenient for rapid optimization of the extraction process. The detection and quantification limits are 8 and 27μgmL−1, respectively. The within-day and between-day precision (R.S.D.) are 1.6–3.2% and 2.8–4.2%, respectively. Compared with off-line detection, the proposed method may provide more rapid measurement and is more convenient for obtaining continuous measurements. [Copyright &y& Elsevier]